Amylin is a 37-amino acid peptide cosecreted with insulin from the beta cells of the pancreatic islets. It was first reported by Cooper et al in Proceedings of the National Academy of Sciences, USA 84, 8628 (1987) and is the subject of European Patent 289287. Amylin has the following peptide sequence:
(SEQ ID NO:1)Lys-Cys-Asn-Thr-Ala-Thr-Cys-Ala-Thr-Gln-1                5                 10 Arg-Leu-Ala-Asn-Phe-Leu-Val-His-Ser-Ser-11               15                20 Asn-Asn-Phe-Gly-Ala-Ile-Leu-Ser-Ser-Thr-21              25                 20 Asn-Val-Gly-Ser-Asn-Thr-Tyr31                35
The native molecule contains a disulphide bridge between the cysteine residues shown at positions 2 and 7 in the primary structure, is amidated at its COOH— terminus, and is formed as a propeptide.
European Patent 289287 reports a number of biological effects including enhancement of hepatic glucose output, increased production of lactate from skeletal muscle and reduced action of insulin in skeletal muscle.
Amylin is also reported in European Patent 408284 as having value for treatment of bone disorders and calcium imbalance. The patent specification attributes the activity of amylin to an inhibition of osteoclast motility. It is also reported in WO 96/02269 as stimulating bone growth through stimulating osteoblast proliferation.
Adrenomedullin is a 52-amino acid peptide first described in 1993 by Kitamura et al (Kitamura, K., et al. Adrenomedullin, a novel hypotensive peptide isolated from human pheochromocytoma. Biochem. Biophys. Res. Commun. 192:553-560 (1993)). It is present in normal adrenal/medulla and in many other tissues including the atria, ventricles, endothelial cells, lungs, brain, kidneys and bone.
Adrenomedullin shows approximately 20% sequence identity with amylin and can therefore be termed a related peptide (Muff, R., et al. Calcitonin, calcitonin gene-related peptide, adrenomedullin and amylin: homologous peptides, separate receptors and overlapping biological actions. Eur. J. Endocrinol. 133:17-20 (1995)). Both peptides have an NH2 terminal ring created by a disulphide bond and are amidated at their COOH terminals.
Like amylin, adrenomedullin is also reported to have a range of activities. It is a potent vasodilator. It also has value in the treatment of bone disorders. This is primarily through an ability to stimulate osetoblast activity and proliferation in vitro and in vivo (Cornish, J., et al. Adrenomedullin is a potent stimulator of osteoblastic activity in vitro and in vivo. Am. J. Physiol (Endocrinol Metab) 36:E1113-E1120, (1997)).
However, to date, there has been no report of either of the peptides amylin or adrenomedullin, as having any effect on chondrocytes. It is the applicants finding that both of these peptides are effective in the stimulation of chondrocyte proliferation and therefore on the growth of both cartilage and lineal bone. This effect is believed to be mediated through a single receptor on chrondrocytes which underlies the applicant's invention.